This invention is directed to a method for recoating a substrate with a basecoat/topcoat system in which the topcoat composition comprises a silane polymer. In particular, this invention is directed to a method for obtaining recoat adhesion, especially during in-line and end-of-line repair of the finish of an automobile or truck during their original manufacture.
In order to protect and preserve the aesthetic qualities of the finish on an automobile or other vehicle, it is generally known to provide a clear (unpigmented or slightly pigmented) topcoat over a colored (pigmented) basecoat, so that the basecoat remains unaffected even on prolonged exposure to the environment or weathering. This is referred to as a topcoat/basecoat finish. It is also generally known that silane polymers provide coatings having improved chemical or etch resistance. Exemplary of prior art patents disclosing silane polymers for coating are U.S. Pat. No. 4,368,297; U.S. Pat. No. 4,518,726; U.S. Pat. No. 4,043,953; and Japanese Kokai 57-12058.
Commercialization of silane finishes have been hindered by several significant or even critical technical hurdles. For example, a commercially practical finish, among other requirements, must have adequate recoat adhesion, since defects in the finish may occasionally occur during the original manufacturing process, necessitating on-site repair. A commercially practical finish must not be problematic or difficult to apply.